Types of mutation

Source video.

Summary:

Codon is a set of 3 base pairs in the RNA that codes for a Amino acid, that in return forms a protein. There are 64 possible codes with 4 base pairs, but just 20 Amino acids. Hence, there is redundancy in the mapping, and some extra codes possible for Start and stop.

Classification based on how they affect the DNA

1. Point mutation: A single base pair changes in the DNA.
2. Frame-Shift Mutation: A base pair is deleted or new base pair is introduced in the middle of a code. This cause that codons to be read in a wrong manner. Some references say that frameshift mutation is a type of point mutation.

Classification based on how they affect the resulting protein

1. Non-sense mutation: When RNA sequence becomes a STOP! codon instead of a regular codon.
2. Missense mutation: Any mutation that changes an amino acid from one to the other.
1. Conservative mutation: The new amino acid is of the same type as the original.
2. Non-conservative mutation: The new amino acid is of different type as that of the original.
3. Silent mutation: RNA codon changes but the resulting Amino acid does not change because there is redundancy in the map from codon to amino acid.

Point mutations may arise from spontaneous mutations that occur during DNA replication. The rate of mutation may be increased by mutagens. Mutagens can be physical, such as radiation from UV rays, X-rays or extreme heat, or chemical (molecules that misplace base pairs or disrupt the helical shape of DNA). Mutagens associated with cancers are often studied to learn about cancer and its prevention.